1. Field of the Invention
The present invention relates to a vehicular lamp. More particularly, the present invention relates to a lighting circuit for lighting a vehicular lamp including a plurality of light sources.
2. Description of the Related Art
Conventionally, a switching regulator that supplies power to a light source of a vehicular lamp is known as disclosed in see Japanese Patent Application Laid-Open No. 2001-215913, page 3 and FIG. 7, for example. An output voltage of the switching regulator is controlled based on a current flowing in the light source, for example. Moreover, a vehicular lamp is known which switches brightness of the light source by switching resistance of a resistor connected in series with the light source as disclosed in Japanese Utility Model Laid-Open No. 61-48836, page 1, for example.
In a vehicle, various light sources such as a stop lamp and a taillight are mounted. Thus, in a case of driving these various lamps by the switching regulator, there was a problem that the switching regulator should be provided for each of the light sources, thus increasing the cost. In addition, in a case where the current flowing in the light source is limited by using the resistor connected in series with the light source, there was a problem that power consumption of the vehicular lamp increased.